From the nodejs source code (LOC 179), we have the following:

EventEmitter.prototype.once = function(type, listener) {



  /** ... **/



  function g() { /** ... **/ }



  g.listener = listener; // => ???

  this.on(type, g);



  return this;

};

So far, my thinking goes like this:

EventEmitter.once() sets an event of type and removes it immediately once the callback listener has been called via the g(). But what really does the line g.listener = listener; do?

Does it add a property listener which is a function to the function object created by the constructor g() at the time of invocation?